Chemoselective deprotonative lithiation of azobenzenes. Reactions and mechanisms Supporting Information Thi Thanh Thuy Nguyen, Anne Boussonnière, Estelle Banaszak, Anne-Sophie Castanet, Kim Phi Phung Nguyen, and Jacques Mortier* Université du Maine and CNRS UMR 6283, Institut des Molécules et Matériaux du Mans, Faculté des Sciences et Techniques, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, and Université Nationale de Ho-Chi-Minh-Ville, École des Sciences Naturelles, Laboratoire de Chimie Organique, 283/2 Nguyen Van Cu. arrondissement 5, Ho Chi Minh Ville, Viêt Nam jacques.mortier@univ-lemans.fr S1
Table of Contents A- Structural determination of hydrazine 3b and azobenzenes 21-31... 3 A1-1-(sec-Butyl)-1,2-diphenyl-2-(trimethylsilyl)hydrazine (3b)... 3 A2-2-Methoxy-5-(phenyldiazenyl)benzoic acid (21) and 5-methoxy-2-(phenyldiazenyl)benzoic acid (22). 4 A3-1-(4-Methoxy-3-(trimethylsilyl)phenyl)-2-phenyldiazene (23)... 6 A4-2-Fluoro-5-(phenyldiazenyl)benzoic acid (24)... 6 A5-2-(Diethylcarbamoyl)-5-(phenyldiazenyl)benzoic acid (25)... 8 A6-2-Methoxy-6-(phenyldiazenyl)benzoic acid (26)... 9 A7-2-Fluoro-6-(phenyldiazenyl)benzoic acid (27) and 2-fluoro-4-(phenyldiazenyl)benzoic acid (28)... 10 A8-2-(Diethylcarbamoyl)-4-(phenyldiazenyl)benzoic acid (29)... 12 A9-2-Fluoro-3-(phenyldiazenyl)benzoic acid (30) and 3-((2-carboxyphenyl)diazenyl)-2-fluorobenzoic acid (31)... 15 B- NMR spectra of hydrazines 3a, 3b and azobenzenes 19, 21-31... 18 S2
A- Structural determination of hydrazine 3b and azobenzenes 21-31 A1-1-(sec-Butyl)-1,2-diphenyl-2-(trimethylsilyl)hydrazine (3b) sbu TMS 3b The presence of invertomers was confirmed by variable-temperature 1 H NMR spectra in DMSO-d 6. The CH 3 c and CH 3 d signals at ambient temperature appear respectively as two doublets (δ H = 1.29 and 1.17) and two triplets (δ H = 1.00 and 0.92) (Figure 1) that coalesce on warning the sample to 90 C (Figure 2). Degradation products were observed above 60 C. 9H TMS 9H TMS c a d b TMS 3b 3Hc 3Hc 3Hd 3Hd 2Ha 2Hb 2Hb Figure 1. 1 H NMR spectrum of 3b in DMSO-d 6 at rt S3
* * * * sample recooled down to 26 C Asterisks (*) denote degradation products Figure 2. Variable-temperature 1 H NMR spectra of 3b (δ = 1.4-0.7 ppm) A2-2-Methoxy-5-(phenyldiazenyl)benzoic acid (21) and 5-methoxy-2- (phenyldiazenyl)benzoic acid (22) MeO MeO 21 22 The 1 H- 1 H coupling patterns of 21 and 22, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,4-trisubstituted aromatic ring. Therefore the and S4
MeO groups are located in the same ring. Proof for the position of the group was gathered by the NOESY technique. For 22, the methoxy group shows clear interactions with the hydrogens at 7.90 ppm and 7.20 ppm (Figure 4). The methoxy group is flanked by two hydrogens and the group is located in the position ortho to the N=N-Ph group. For 21, the methoxy group shows correlation with the hydrogen at 7.19 ppm, which is consistent with the located in the position ortho to OMe (Figure 3). dd J = 8.9 and 2.6 Hz H d J = 8.9 Hz H dd J = 9.0 and 2.9 Hz d J = 9.0 Hz H H H 3 CO H d J = 2.6 Hz H 3 CO H d J = 2.9 Hz 21 22 Figure 3. Key NOESY correlations of compounds 21 and 22 H A H C H B OCH 3 H A H B H 3 CO H C 22 NOESY Figure 4. NOESY spectrum of compound 22 S5
A3-1-(4-Methoxy-3-(trimethylsilyl)phenyl)-2-phenyldiazene (23) MeO TMS 23 The 1 H- 1 H coupling patterns of 23, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,4-trisubstituted aromatic ring. Therefore the TMS and MeO groups are located in the same ring. The NOESY spectrum of 23 reveals a correlation between the TMS and the methoxy signals (Figure 5). As a result, the TMS substituent is located in the position adjacent to the methoxy group. TMS OCH 3 H A H B H 3 CO H C TMS 23 NOESY H C Figure 5. NOESY spectrum of 23 A4-2-Fluoro-5-(phenyldiazenyl)benzoic acid (24) F 24 S6
Similarly, the 1 H- 1 H coupling patterns of 24, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,4-trisubstituted aromatic ring: the F and substituents are then located in the same ring. Structural assignment was carried out with the aid of HMBC. For the CH coupling in benzene ring, only the meta (vicinal) coupling 3 J CH is usually resolved. 1 Strong cross peaks in the HMBC spectrum between aromatic H A (δ H 8.64) and C-F (δ C 163.9) and (δ C 168.5) indicate that H A is ortho to the substituent and meta to the fluorine. Compound 24 is therefore identified as beeing 2-fluoro-5-(phenyldiazenyl)benzoic acid. F HOOC 24 H A Figure 6. Key HMBC correlations of 24 H A C-F Figure 7. HMBC spectrum of 24 1 Breitmaier, E. Structure Assignments By NMR in Organic Chemistry: A Practical Guide. John Wiley & Sons: Chichester, U.K., 2002. S7
A5-2-(Diethylcarbamoyl)-5-(phenyldiazenyl)benzoic acid (25) Et 2 NOC 25 The 1 H- 1 H coupling patterns of 25, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,4-trisubstituted aromatic ring (Figure 8): the and CONEt 2 substituents are located in the same ring. Strong HMBC correlations are observed for CONEt 2 (δ C 170.4), C-N=N-Ph (δ C 152.5) and C- (δ C 128.9) and the hydrogen at 7.45 ppm, assigning the latter signal to H A (Figure 9). Additional HMBC correlations, COSY cross peaks and magnitudes of the 1 H- 1 H coupling constants are consistent with the proposed structure. Key COSY correlations Key HMBC correlations dd J HH = 8.2 ; 2.0 Hz d J HH = 8.2 Hz H A H B H A H B O H C NEt 2 d J HH = 2.0 Hz O H C NEt 2 25 25 Figure 8. Key COSY and HMBC correlations of 25 S8
HC H B H A C- C- N=N- Ph CONEt 2 Figure 9. HMBC spectrum of 25 A6-2-Methoxy-6-(phenyldiazenyl)benzoic acid (26) OMe 26 The COSY spectrum of 26 shows that three of the eight aromatic hydrogens belong to the same aromatic ring and the magnitude of the 1 H- 1 H coupling constants ( 8 Hz) is characteristic of the presence of three adjacent aromatic hydrogens (Figure 10). 3 J = 8.1 Hz H 3 J = 8.2 Hz H H OCH 3 26 Figure 10. Key COSY correlations of 26 S9
A7-2-Fluoro-6-(phenyldiazenyl)benzoic acid (27) and 2-fluoro-4-(phenyldiazenyl)benzoic acid (28) F HOOC 27 F 28 The COSY spectrum of 27 shows again that three of the eight aromatic hydrogens belong to the same aromatic ring. The magnitude of the 1 H- 1 H coupling constants ( 8 Hz) is characteristic of three adjacent aromatic hydrogens (Figure 11 and Figure 12). 3 J HH = 8.1Hz H A 3 J HH = 8.1Hz H B H c F 27 Figure 11. Key COSY correlations of 27 H A HB H C Figure 12. COSY spectrum of 27 S10
For 28, proof for the location of the group was gathered from the magnitudes of 1 H- 1 H and 1 H- 19 F coupling constants and by COSY technique. The 1 H- 1 H coupling patterns of 28, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,4- trisubstituted aromatic ring (Figure 14). The splitting pattern of hydrogen at 7.72 ppm is consistent with hydrogen H C located ortho to the fluorine ( 3 J H-F = 11.6 Hz,) and meta to H A ( 4 J H-H = 1.7 Hz). The location of the substituent is further supported by the analysis of the 1 H-decoupled 13 C spectrum of 28. The splitting pattern of the residue (δ C 164.7, small doublet, J C-F = 3.5 Hz), is inconsistent with structure 28 (Figure 15) for which the substituent is located para to the fluorine atom. 3 J HH = 8.1Hz H A H B J H-F = 8.0 Hz HOOC F J C-F = 3.5 Hz 28 H C 4 J HH = 1.7Hz J H-F = 11.6 Hz Figure 13. Key coupling constants of 28 H B H A H C H C H A H B S11
Figure 14. COSY spectrum of 28 J C-F = 0 Hz H B H A F 28' H C Figure 15. Structure 28 A8-2-(Diethylcarbamoyl)-4-(phenyldiazenyl)benzoic acid (29) HOOC 29 CONEt 2 The 1 H- 1 H coupling patterns of 29, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,4-trisubstituted aromatic ring. The 1 H- 1 H coupling shows that the proton at 7.83 ppm (J HH = 1.6 Hz) has no hydrogen in its ortho position and therefore can be assigned to H C (Figure 16). CONEt 2 shows NOESY correlation (Figure 16) and HMBC correlation (Figure 17) with only one aromatic hydrogen (H C ). Therefore, CONEt 2 is located ortho to H C and there is no other proton ortho to CONEt 2. Considering all these data taken together, compound 29 is identified as the 2-(diethylcarbamoyl)-4-(phenyldiazenyl)benzoic acid. The proposed structure was further supported by additional HMBC correlations (Figure 18). S12
H B H A HC H A H B HOOC 29 O H C Et N Et d J = 1.8 Hz NOESY Figure 16. NOESY spectrum of 29 S13
H C H A H B HOOC H C Et O N H C CH 3 H 29 Figure 17. HMBC spectrum of 29 H A H B HOOC O H N C H H C Et CH 3 29 Figure 18. Selected HMBC correlations of 29 S14
A9-2-Fluoro-3-(phenyldiazenyl)benzoic acid (30) and 3-((2-carboxyphenyl)diazenyl)-2- fluorobenzoic acid (31) F F 30 31 The 1 H- 1 H coupling patterns of 30, obtained from the COSY experiment, show that three of the eight aromatic hydrogens belong to a 1,2,3-trisubstituted aromatic ring. Cross peaks in the HMBC spectrum between aromatic H (δ H 8.16) with C-F (δ C 160.0) and (δ C 168.6) indicates that this hydrogen is ortho to the substituent and meta to the fluorine (Figure 19 and Figure 20). From the above assigments, the structure of compound 30 was attributed to 2-fluoro-3- (phenyldiazenyl)benzoic acid (30). COSY correlations HMBC correlations H A H B H C F 30 Figure 19. Key COSY and HMBC correlations of 30 S15
H C C-F Figure 20. HMBC spectrum of 30 HRMS analyses indicate that 31 is a diacid (molecular formula: C 14 H 9 FN 2 O 4 ). The 1 H- 1 H coupling patterns of 31, obtained from the COSY experiment, show that three of the seven aromatic hydrogens belong to a 1,2,3-trisubstituted aromatic ring. Cross peaks in the HMBC spectrum between aromatic hydrogen H C (δ H 8.10) and C-F (δ C 160.7) and (δ C 166.6) indicate that H C is ortho to the substituent and meta to the fluorine (Figure 21 and Figure 22). For the disubstituted aromatic ring, the HMBC spectrum shows cross-peaks between aromatic hydrogen H A' (δ H 7.88) and C OOH (δ C 170.5) and C-N=N-Ar (δ C 152.8) (Figure 22). These data supports the structure proposed in Figure 21. COSY correlations HMBC correlations H C' H A H D' H B' H B H C HOOC' F 31 H A ' Figure 21. Key COSY and HMBC correlations in 31 S16
H C C-F H A ' C-N=N- C' OOH Figure 22. HMBC spectrum of 31 S17
B- NMR spectra of hydrazines 3a, 3b and azobenzenes 19, 21-31 nbu TMS 3a S18
nbu TMS 3a S19
sbu TMS 3b S20
sbu TMS 3b S21
CONEt 2 19 S22
CONEt 2 19 S23
MeO 21 S24
MeO 21 S25
MeO 22 S26
MeO 22 S27
MeO TMS 23 S28
MeO TMS 23 S29
F 24 S30
F 24 S31
F 24 S32
Et 2 NOC 25 S33
Et 2 NOC 25 S34
OMe 26 S35
OMe 26 S36
F 27 S37
F 27 S38
F 27 S39
HOOC F 28 S40
HOOC F 28 S41
HOOC F 28 S42
CONEt 2 HOOC 29 S43
CONEt 2 HOOC 29 S44
F 30 S45
F 30 S46
F 30 S47
F 31 S48
F 31 S49
F 31 S50